A red-tailed hawk hovers aloft over the 101 in the midday sun, scanning a nearby hillside for signs of life. This raptor’s keen eyes catch the rustle of grass, a long tail disappearing into the vegetation: the telltale signs of a waiting meal. Pest control is on the clock, and this hardworking mom has mouths to feed back at her nest. She suddenly makes her move: wings tucked, in a steep dive heading straight for an unsuspecting rodent who today has the misfortune of being in the wrong place at the wrong time. Success! With lunch grasped tightly in her sharp talons, the hawk heads back to her hungry chicks, job well done.
But what she doesn’t know is that the now ex-rat in her grip is a ticking time bomb: because a few days ago that rat fed on what it thought was a tasty snack in a black box in the back alley of an apartment complex, and he’s been feeling sick ever since. His days were numbered even before the hawk’s shadow fell across his path. And now, when this hawk shares this meal with her chicks, the anticoagulant rodenticide concentrated in this rat’s organs will do just what it says on the box. In addition to killing the pest, it will kill the pest control too.
Hang on, I thought we banned rodenticides! It was all over the news.
You’re probably thinking of AB 1788; this bill, the California Ecosystems Protection Act, went into effect January 1, 2021 and was a big win for wildlife. The bill made the strong case for the harm caused by second-generation anticoagulant rodenticides (SGARs) to the very predators that are naturally working to control the rodent populations in the wild and in our cities. Prior to this bill, California had limited the over-the-counter sales of these SGARs in 2014, but studies conducted on wildlife in the intervening years showed no significant decrease in rodenticide exposures and associated deaths: not surprising, since SGARs were still widely in use by commercial pest control companies, and available via mail from online retailers. AB 1788 is an even stricter regulation of the use of SGARs; however, the bill makes several notable exceptions for public health activities, protecting water supply infrastructure, agricultural production and food storage facilities, medical waste facilities, and use on offshore islands to eradicate invasive species. So while it’s significantly harder for the average California consumer to procure SGARs or the services of pest control companies who utilize them, these deadly poisons are unfortunately still out there.
First generation? Second generation? What’s the difference?
First-generation anticoagulant rodenticides (FGARs) were developed in the 1940s and 50s, and work by disrupting blood clotting, causing internal bleeding and eventual death over the course of a few days to a couple weeks. FGARs like diphacinone or chlorophacinone are still widely available for consumer purchase. You might remember the shocking photo of our late great celebrity cat P-22, back in 2014 when he was captured and treated for mange; tests revealed he had both of the aforementioned FGARs in his system. Rodenticide poisoning weakens an animal’s immune system, and this parasitic skin condition is one of the ways it can present.
Second-generation anticoagulant rodenticides (SGARs) are more potent than first-generation, and may only require one feeding to be fatal. These blood-thinning toxins include brodifacoum, bromadiolone, difenacoum, and difethialone, and all cause massive hemorrhaging and death within several days. However, the toxins themselves have a half-life of over 100 days and so their potency persists as they work their way up the food chain to apex predators. The average person or company putting out these poison baits is thinking only about solving the immediate problem at hand: when in fact, poisoning the ecosystem has the opposite effect in the long-term, actually increasing the population of rodents by eliminating their predators. These predators have a much slower reproduction rate than their prey, so in the time it takes to replace one apex predator lost to rodenticide, many more rapidly reproducing rodents will have set up shop in your neighborhood.
But I see those black boxes all over the city and my neighborhood. Don’t the rodents get trapped inside after they’ve eaten the bait? How are predators eating them?
Contrary to popular belief, these bait boxes aren’t rat coffins. They are designed so that rodents can go in and out, returning to feed on the bait multiple times and/or bringing back bait to their young. And once the now-poisoned rodents leave these boxes, they often present an easy meal to the neighborhood cat or great-horned owl as they weaken, succumbing to the poison’s effects. These bait boxes may say they’re tamper-proof, safe for pets and children, but on average every year in the United States, tens of thousands of children and pets accidentally consume rat poison.
But my pest control company says their methods are safe!
“Safe poison” is an oxymoron: if a pest control company tells you their product is non-toxic, check to see if it contains any of these FGARs like diphacinone and chlorophacinone, or the nerve toxin bromethalin, all of which are still available to consumers. Even though the FGARs are less potent and slower acting than SGARs, they still have potentially lethal capacity if consumed directly or indirectly by children, pets and wildlife. Bromethalin, which acts by way of causing respiratory distress and death within 24-48 hours, is lethal if consumed directly.
I just discovered I have mice in my house! What am I supposed to do now if I can’t use rodenticides?
OK, so you heard the distinctive skitter of tiny rodent feet in your walls, or found their dreaded droppings in your cupboard. Don’t go reaching for the poison! First: focus on exclusion. How are the mice getting into your home? Seal up any entry points. Trim tree limbs and vegetation away from walls and the roof. Reduce the amount of welcoming rodent shelter available around the house like woodpiles and ivy. What’s attracting them to your home? Keep your trash bins closed; make sure you’re not leaving pet food out; clean up birdseed from the ground under your feeders. Old-fashioned snap traps are still a quick and efficient way to control unwanted houseguests; newer electronic traps work well, although these traps are more expensive. NEVER use glue traps: they are a slow, inhumane way for any animal to die, and non-target wildlife like birds and lizards often get stuck by accident. If you’re looking to hire a pest control company, ask around for one that practices Integrated Pest Management and verify that they aren’t using poisons. Some companies are also beginning to implement rodent birth control as a non-toxic strategy for long-term population reduction. And, if all that doesn’t have you convinced, an unintended consequence of using rodenticides is that this out-of-sight, out-of-mind approach may result in a decaying rat in your walls: it may be out of sight but certainly not out of scent.
The rodent problem in our city is of our own making, but it’s a problem we can solve with the aid of our furred, feathered, and scaly neighbors: and without anticoagulant rodenticides. Help us protect current and future generations of our all-natural pest control. Let the predators do their job, and leave the poison on the shelf.
You’re preaching to the choir. I already don’t use rodenticides and love watching the wildlife in my neighborhood. What else can I do to help?
One great way to help the wildlife in your neighborhood is to cultivate native plant habitat where you live: no matter how small the space: to increase the biodiversity of your area and connect to other nearby habitats, thus creating your own version of a wildlife corridor and providing natural sources of food and shelter for your local animals.
On the subject of food, do not feed wildlife! Maybe you saw someone hand-feeding their illegal pet raccoon on social media and you thought it looked cute, but raccoons and other wild animals can be vectors for many diseases including rabies, and wild animals that become too habituated to humans lose their instinctual fear and can become aggressive. Animals have specialized diets, and those that become too reliant on human food will become malnourished and get sick or die from eating the wrong foods. There are others ways to show your love for wildlife than endangering their lives for a photo op!
If you do see any animal that appears sick, injured, or behaving suspiciously, do not attempt to touch it, capture it, or feed it without first consulting wildlife care professionals. There is, for example, currently an outbreak of highly pathogenic avian influenza particularly in raptors and waterfowl, and very strict precautions must be taken when handling potentially infected wildlife.
Also, it’s now spring which means it’s baby season! Don’t assume baby animals on their own are abandoned: their parents may have left them in what they thought was a safe spot, and they are nearby searching for food. Observe from a safe distance to see if the parents return, and if you are still concerned, please call a licensed wildlife rehabilitator or rescue like California Wildlife Center, International Bird Rescue Center, Marine Mammal Care Center, or Ojai Raptor Center for further instructions. You may do more harm than good by trying to “help” a baby animal that doesn’t need it. And please hold off on tree trimming until the fall or winter, after nesting season.
And finally, for the sake of your beloved cats’ wellbeing and for the wellbeing of all our wildlife, keep your cats indoors!
~Angela Woodside, FoGP member
Current Rodenticide Legislation [AB 1322]
Assemblymember Laura Friedman is leading the legislative charge against the use of diphacinone, the agent that made P-22 sick in 2014.
Recently, FoGP funded lab testing of a young bobcat, confirming it had a high load of diphacinone.
AB 1322 would extend the existing moratorium on dangerous second generation anticoagulants, and adds diphacinone, the most widespread rodenticide used today. It has a high probability of affecting non-targeted wildlife.
There is little doubt that most of the use of this agent is by pest control “professionals” in residential neighborhoods.
Help us support AB 1322!